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Finding the Fourth Proportional to 928.26, 1,280.61 and 840.78

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Solution

The fourth proportional to 928.26, 1,280.61 and 840.78 is: 1,159.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.26 : 1,280.61 = 840.78 : x
  2. Step 2: Convert to fraction form
    928.26/1,280.61 = 840.78/x
  3. Step 3: Cross multiply
    928.26x = 1,280.61 × 840.78
  4. Step 4: Simplify right side
    928.26x = 1,076,711.28
  5. Step 5: Solve for x
    x = 1,076,711.28/928.26
  6. Step 6: Final answer
    x = 1,159.92

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.